Grinding mill



T. BRAGARD March l1, 1930.

GRINDING MILL Filed July 3, 192g Patented Mar. 11, 1930,

UNITED STATES THEODOR BRAGARD, OF HAMBURG, GERMANY, ASSIGNORWALZENMUKLEN-GESELLSCHAFT MIT BESCHBANKTER GERMANY TO FIRM OF MzCAO-HAFTUNG, OF HAMBURG,

GRINDING MILL Application led July 3, 1928, Serial No. 290,115, and inGermany June 9, 1927.

This invention relates in the first place to a grinding device in whichthe end faces of several planetarily driven grinding discs cooperatewith an annular grinding disc located within a casing, and in the secondplace to a mill in which the planetarily rotatable grinding discs arerigidly connected with rolls performing planetary rotation around acentral shaft, said rolls belonging to a roller mill, known per se, ttedin the same casing. The combined mill in which the goods are preferablyfirst fed to the set of rolls and are eX- pelled by the pressure of thelatterdirectly to the set of grinding discs is particularly adapted forthe treatment of plastic masses, such as paints, which can ,be ground tothe finest sizes. Preferably all the grinding bodies are formed of hardporcelain and all the metallic parts which contact with the goods areenamelled. l v

In the accompanying drawing is illustrated by way ofeXample aconstruction according to the invention. f-

Fig. 1 is a vertical longitudinal section through the combined mill.Fig. 2 shows a modified form of feeding device. Fig. 3 is a section ofthe line A-A of Fig. 1 viewed from the left and shows the rotatablegrind'- ing discs in one position. Fig. 4 is a section on the line AA ofFig.v 1 showing the grinding discs in a position of 180 displaced fromthe position of Fig. 3. Fig. 5 is a section on the line A-#A of Fig. 1viewed from the right. Fig. 6 is a section on the line B-B of Fig. 1viewed from the left. Fig. 7 is a section on the line B-B of Fig. 1viewed from the right.

As shown in the drawing, the invention is incorporated in a millincluding a central roll 1 and rolls` 2 performing planetary rotationaround the roll 1, it being understood, that the rolls 1 and 2 arepreferably conical as shown. The central roll is driven by means of theshaft 3 and the belt-pulley l mounted on said shaft. The central roll 1is provided at its ends with spur gears 5 meshing with spur gears 6 onthe ends of the rolls 2. The gears 6 mesh With circular racks 7 in thecasing. The rolls 1 and 2 preferably consist of hard porcelain and thecasing 8 is provided with a lining 9 which if the rolls 1 and 2 areconical is also conical and also consists of vhard porcelain.

The goods are fed to the rolls 1 and 2 by way of a hopper 1() and a Worm11, the axis of which may be disposed vertically as shown in Fig. 1 ormay, as shown in Fig. 2, be coincident with the shaft'3. A conical valve12 which is vertically adjustable by actuation of a hand wheel 14controlling the lever 13 regulates the delivery of the goods from thehopper 10 to the worm 11.

On the outer faces of the left-hand gears 6 are eccentrically mountedgrinding discs 15 the end faces of which co-operate with a stationaryannular grinding disc 16 having a close fit within the casing. The discs15 depart from circular form, being in the present case of ellipticalform,

The eccentricity and dimensions of the discs 15 which rotate with thegears 6 are such that the said discs 15 in their rotary motionalternately sweep past the point of engagement of the gears 6 with thegear 5 and the points of engagement of the gears 6 with the circularrack 7. The faces of the discs 15 adjacent to the gears 6 are formedwith grooves 17 at the points of maximum eccentricity, the mearrdistance of which grooves from the axes of rotation of the discs 15corresponds about to the radius of the pitch circle of the spur gears 6and which grooves communicate with holes 18 leading to the outer facesof the discs 15. It is thus ensured that the. goods pressed by the rolls1, 2 through the points of engagement of the gears 6 with the gear 5 andthe circular rack 7 will not exercise a binding or choking action at thepoints where the grinding discs 15 sweep past said points of engagement,but can pass through the holes 18 to the outer grinding and rubbing.faces of the discs 15. The stationary annulus 16 is provided as shownin Figs. 5 and 6 with tangential grooves 30 on each side, and its endface which is to the left in Fig. 1 contacts with an additional movablegrinding annulus 19 which is fixed to the shaft 3 by means of a boss 2Oso as to be longitudinally movable along the shaft 3 but rotatable withthe vided on the face which is at the left in Fig..1 with a pocket-likecavity 21 which is found advantageous for effecting good distribution ofthe goods on the grinding faces between 16 and 19. This pocket 21 issomewhat displaced from the vertical in the direction of rotation of thedisc 19.

By axial shift of the shaft 3 it is possible to adjust the intervalsbetween the central roll 1 and the rolls 2. The shaft 3 is provided atthe right-hand end with a throughslot a and abuts through theintermediary of a collar c against a powerful helical spring 22, thecompression of which is adjustable by operation of a set screw 23. Acotter b penetrating the yslot limits the shift of the shaft 3 towardsthe right, it being under-V stood that Fig. 1 shows the rolls spaced attheir furthest distanceapart, that is, the eX- treme right-hand positionof the central roll. Engaging the left-hand end of the shaft 3 is aset-screw 24. Toreduce the spacing of the rolls, the shaft 3 can beshifted to the left by operation of the set-'screws 23 and 24. With thisdisplacement the baseof `the slot a is spaced from the cotter b, and theshaft 3 is then subject only to the actionof the spring 22. The centralroll'l is thus resiliently movable in axial direction which is desirablefor compensating for unforeseen resistance. Also the pressure of therotatable dlsc 19 against the stationary disc 16 is adjustable. Toeffect such adjustment there is rovided a screw-threaded bush which ars,preferably through the intermediary of a ball-bear-ing 26, against theboss 20, and by adjustment of which bush the boss together with the disc12 can be shifted axially. If the disc 16 is so uided in the casing thatit can shift in the ongitudinal direction of the latter but cannotrotate, then by adjustment of the screw-threaded bush 25 also thepressure between the disc 16 and the discs 15 can be varied. Thedischarge of the ground goods is effected at 27. In front of the rolls 1and 2 is a distributing` chamber 28 to which the goods are fed by theworm 11. Due to the eculiar movement of the planetarily rotata. leelliptical grinding discs 15 there is effected a pumping action whichcontinuously pumps forward the mass which has attained in the roll milla sufficient fineness to pass between thediscs and which presses thegoods through the'grinding discs located at the end of the mill. Theentire grinding operation is effected positively from the feed worm upto the point of discharge. The elliptical discs 15 are provided on theirend faces with crossing grooves 31 f Figs. 3 and 4) so that the suckingeffect of these discs varies continuously and their surfaces wear andact uniformly.

In the position shown in Fig. 3 the sucking action is effected withregard to the upper discs on their right-hand side, while in the'position shown in Fig. 4, in which the limit of the throw is towards thecentre, the suckin action is effected on the other side.

he set of grinding discs may be added to if desired by incorporatingadditional grinding discs as shown in Figs. 6 and 7.

I claim 1.- A grinding mill incorporatinga casing, an annular grindingdisc located in said casing, a plurality of planetarily driven grindingdiscs the end faces of' which co-operate with said annular disc,grinding rolls connected with said planetarily driven grinding discs.and a central roll about which the first named rolls rotate and whichis externally driven, intermeshing spur gears on the rolls toplanetarily drive the outer rolls from' the central roll, the end facesof the spur gears at the exit ends of the planetary rolls carrying themovable discs.

2. A grinding mill incorporating a casing, an annular grinding disclocated in said casing, a plurality of planetarily driven grinding discsthe end faces of which co-operate with said annular disc, grinding rollsconnected with said planetarily driven grinding discs and a central rollabout which the first named rolls rotate, and which is externallydriven, intermeshing spur gears on the rolls to planetarily drive theouter rolls from the central roll, the end faces of the spur gears atthe exit ends of the planetary rolls carrying the movable discs, themovable discs being elliptical and of such dimensions or of sucheccentricity that they alternately sweep past the points of engagementof the spur gears on the planetary rolls with the spur gear on thecentral roll, and the points of engagement of the first mentioned gearswith a circular rack within the casing.

3. A mill such as claimed in claim 1, further characterized in that thefaces of the movable'discs adjacent to the spur gears are provided atthe points of maximum eccentricity with grooves the mean distance ofwhich from the axes of rotation of the said discs is equal to about theradius of the pitch circle of the spur gears and which communicate withholes` leading to the outer faces of the discs.'

4. In a grinding mill, a' casing, a stationary grinding disk in saidcasing, other grinding disks mounted in said casing and of ellipticalform and being facially presented to the adjacent face of the stationarygrinding disk to coact therewith to grind material delivered between thefaces of the disks, and means for imparting planetary motion to theelliptical grinding disks.

5. In a grinding mill, a casing, a conical grinding roll rotatablymounted therein, an annular grinding disk within the casing concentricto the axis of rotation of said roll, a lplurality of grinding disksmounted in the casing adjacent the ends of conical grinding rolls, andofelliptical form and presented facially tothe adjacent face of the firstmentioned disc,l andadapted to cooperate with said first-mentioned disc,conical grindin rolls rotatable within the second mentione grindingdisks and about the first mentioned roll( and means for imparting rotarymotion to the first and second mentloned grinding rolls and ,to the sa'delliptical grinding disks.

6. In a grinding mill, a casing; a conical grindingroll rotatablymounted therein, an annular grinding disk within the casing concentricto the axis of rotation of said roll,

' a plurality of grinding disks mounted in the from the casing asdelivered from said disks.

casing .and of elliptical form and presented facially-to the adjacentface of the irst mentioned disks and cooperating therewith, conicalgrinding rolls rotatable with the second mentioned disks and about theirstmen tioned roll, and cooperable therewith, 'and on the ends of whichsaid plurality of grinding ,disks are-mounted means, for impartingmotion to the first and second mentioned grinding rolls and to the saidelliptical grinding disks, means within the casing for feeding thematerial to be ground, to the rolls, at the ends thereof remote fromthesaid grinding disks, and means for delivering the ground material 7.In a grinding mill, a casing, a conical grinding roll rotatably mountedtherein, an

annular grinding ydisk within the casing concentric to the axis ofrotation of said roll, a plurality of grinding disks mounted in thecasing and of elliptical form and resented facially to the adjacent faceof the rst mentioned disk and cooperating therewith, conical grindingrolls rotatable with the second mentioned grinding disks and about thefirst mentioned roll and cooperable therewith, the

' said plurality of disks being mounted adja- "cent the ends of saidconical grinding-rolls, a

grinding disk rotatable with the first mentioned grinding roll andcoacting, facially, with the other face of the annular grinding disk,and means for imparting rotary motion to the first and second mentionedgrinding rolls and to the said elliptical grinding disks.

Intestimony whereof I have signed my name to this specification.

THEODOR BRAGARD.

